1. Field of the Invention
The invention relates to a dyestuff composition for gradually dyeing hair by atmospheric oxidation wherein an adherent dyestuff composition contains a dye component which becomes entrapped in hair fibers when the dyestuff composition is rinsed from the hair and which results in the gradual development of color in the hair due to atmospheric oxidation of the entrapped dye component. The invention also relates to a process of employing the aforementioned dyestuff composition to gradually dye hair.
2. Background Art
The dyeing of human hair with dyestuff compositions containing an oxidizable dye component is well known. The overwhelming majority of commercial hair dyes employ an oxidizable dye component and a chemical oxidizing agent in an amount which causes a prompt reaction and results in a predetermined target color 30 minutes after application. For instance, U.S. Pat. No. 3,649,159 discloses a hair dyeing process involving application to hair of a dyestuff composition containing primary intermediates, such as oxidizable primary aromatic amines (especially diamines) and substitution products thereof, usually together with aminophenols, in admixture with an oxidizing agent--especially H.sub.2 O.sub.2 or its derivatives, such as urea peroxide, perborates, percarbonates, persulfates, perphosphates, periodares or the like--whereby so-called oxidation dyes are formed in situ on the hair. In the color-forming reaction, the aromatic primary amino groups and phenolic hydroxyl groups are oxidized in situ to form imino groups and CO groups, and coupling occurs to form polyimino compounds in which the aromatic nuclei assume a quinonoid-like configuration.
It is customary also to include as part of the dye component, color coupling compounds such as a polyhydric phenol--e.g. resorcinol, pyrogallol or the like.
The color reaction of a mixture of a primary intermediate, such as p-phenylene diamine, and a color coupler, such as m-phenylene diamine, is illustrative. First, the p-phenylene diamine is oxidized to p-benzoquinone diimine. Thereafter, there are two simultaneous reactions, one of which is the self-coupling of the p-benzoquinone diimine to produce a brown-colored Bandrowski's base. The other is the reaction of p-benzoquinone with m-phenylene diamine to produce an indamine dye of blue-purple color. By the addition of other primary intermediates and other color couplers to the reaction mixture it is possible to produce additional colored molecular species so that the final color can be adjusted to that which is desired.
Typically, a dyestuff component, comprising primary intermediates and couplers, is solubilized in a suitable carrier at about a 1% concentration. The carrier can be made sufficiently alkaline, typically above pH 9.5, so as to release oxygen from the peroxide salt and accelerate oxidation. It has been found such treatment also swells the hair imbrications or scales so that the carrier and dye component can penetrate the hair fiber.
In general, at least a molecular equivalent or in excess thereof of an oxidizing reagent, relative to the oxidizable diamine or aminophenol, is employed, although somewhat lesser proportions of oxidant can be used. While it is known that atmospheric oxygen can be utilized in hair dyeing, the use of added oxidizing agents has been widely preferred, since the color-forming reaction proceeds more rapidly in the presence of oxidizing agents and the target color can be more readily achieved. Generally the oxidizing agent, such as a peroxide, is kept separate from the dye component and is added just prior to application to the hair. The advantage of oxidizing the primary intermediate and color couplers after they have penetrated the hair fiber is that the final dye molecules are larger than either starting reactant. Thus, the larger dye molecules become trapped in the hair fibers and the coloration produced thereby is very resistant to washing.
Typically, the reaction between a dyestuff composition and an oxidizing agent requires 20 to 40 minutes for a target color to be developed. Thereafter, the unreacted dyestuff is removed from the hair by water rinsing or shampooing. Such compositions have been conventionally combined with conventional hair care surfactants (detergents, wetting agents), so as to facilitate removal of unreacted dye component by rinsing. During rinsing, surfactants and wetting agents routinely employed in commercial dyestuff compositions promote the removal of unreacted dye components that have penetrated the hair fiber, as well the composition left on the surface of the hair. Thus, rinsing commercial dyestuff compositions from the hair essentially terminates the hair color process.
Other types of known oxidative dyes include the derivatives of 4,7-diaminoindazole disclosed by U.S. Pat. No. 4,104,020. These derivatives in combination with a color coupler are oxidized by atmospheric oxygen to give color in a relatively short time, although the use of a chemical oxidizing agent is preferred.
Also known are hair dyeing compositions containing leuco derivatives of indoanilines, such as the diphenylamines disclosed in U.S. Pat. No. 3,792,090, U.S. Pat. No. 4,008,403 and U.S. Pat. No. 4,008,999. The leuco derivatives, which are, by definition, colorless compounds, are oxidized to their corresponding indolamines by either atmospheric oxygen or an oxidizing agent such as hydrogen peroxide and are said to give better reproducible shades than can be obtained with primary dye intermediates and color couplers. The leuco derivatives tend to form the colored indolamine compound shortly after application, e.g., within 20 minutes, even when oxidized solely by atmospheric oxygen.
Commercial hair dyestuff compositions for women generally employ a dyeing process in which the target color is attained in a single treatment--usually involving application of colorant mixture and oxidant in suitable proportions for the desired target color, allowing the development reaction to proceed for 15 to 60 minutes to develop the desired color followed by washing the hair. Men, however, are usually reluctant to dye their hair such that a complete color change occurs in a single treatment, since they find this accelerated color change undesirable.
A number of preparations have been marketed for men which gradually change or darken hair color by repeated applications of the dyeing composition at selected intervals, and maintenance of the final desired coloration is effected by further applications at less frequent intervals. Gradual darkening of hair has been produced by repeated application of an air oxidation dye color mixture which is left on the hair as a hair grooming composition. The hair is not rinsed or shampooed after application, and atmospheric oxygen is relied upon to develop the coloration, as disclosed, for example, by U.S. Pat. Nos. 3,920,384 and 4,054,413. This method, although widely used, may be improved by reducing the time the composition is left on the hair since certain users do not like to leave the composition on the hair.
It was also known to modify the depth of shade by varying the concentration of the colorant, as taught by U.S. Pat. Nos. 305,057, 1,019,576, 2,185,467, 3,128,232 and Br. Patent No. 12,902/99, not only with oxidation color mixtures, but also with pyro-gallo-Ni salt mixtures and direct dyes. Depth of shade has also been controlled by increasing the duration of the treatment, utilizing phthalaldehyde combined with an alkylolamine as the colorant mixture, as disclosed by U.S. Pat. No. 3,871,818. It is also known, as disclosed in U.S. Pat. No. 4,104,021, to gradually dye hair by successive treatments of the hair with aromatic primary amines in which the concentration of added oxidizing agent is increased at each successive application. After applying the mixture to the hair, color generally develops in from 5 to 15 minutes.
Another method of obtaining gradual coloring of hair employs a low concentration of oxidative dye components (preferably 0.2 to 0.5% by weight) in which most of color development is obtained by atmospheric oxidation within 30 to 60 minutes of application of the preparation, as disclosed by U.S. Pat. No. 4,297,098. The preparation used in this prior art method is to be left on the hair. After 30 to 60 minutes most of the color change is said to occur. This and other formulations containing air oxidizable dyestuffs usually contain surfactants and wetting agents. Upon rinsing, such additives remove any unoxidized dye component from the hair, so that atmospheric oxidation color development is essentially terminated upon rinsing.
Thus, conventional dye formulations, even those containing air-oxidizable dye components, remove unreacted dyestuff components from the hair upon washing via the presence of the surfactants. Further, such formulations seek to develop a target color in a relatively short time after application and cannot tolerate any long term uncontrolled reactions which develop deeper shades.
Accordingly, it is an object of this invention to provide a composition for causing a gradual coloration in the hair over an extended period of time by application of a dyestuff composition to the hair, promptly fixing the dyestuff in the hair fibers and then removing unfixed dyestuff from the surface of the hair.
It is another object to slowly and imperceptibly develop a desired coloration in the hair by applying dyestuff composition, and rinsing to fix the dyestuff within about 5 minutes after application, wherein no color change is perceptible after unfixed dyestuff is removed.